If you grasp something in your hands, you hold it. Be careful when you hold the puppy — he's so wriggly, and you wouldn't want to drop him!
Hold also means to keep from exhaling. If you forget to hold your breath when you go underwater, you're sure to come up sputtering. The noun hold means the cargo area on a ship or airplane. When you check your bag, it's stored in the hold of the plane during the flight. If you packed your book and your snacks in it, it might make more sense to hold onto it instead.